Potassium-sodium niobate-based energy storage ceramic as well as preparation method and application thereof

Abstract

The invention relates to the field of dielectric energy storage ceramic materials, in particular to potassium-sodium niobate-based energy storage ceramic as well as a preparation method and application thereof. The chemical composition of the potassium-sodium niobate-based energy storage ceramic comprises (1-x) (0.55 K0. 5Na0. 5NbO3-0.45 BaTiO3)-x (Bi0. 5yNa0. 5 + y) Ti0. 9Zr0. 1O3, x is more than 0 and less than or equal to 0.4, and y is more than or equal to-0.05 and less than or equal to 0.1. The potassium-sodium niobate-based energy storage ceramic still keeps excellent energy storage efficiency while having high energy storage density, and can meet the use requirements to a greater extent, specifically, at the room temperature of 100 Hz, the energy storage density of the potassium-sodium niobate-based energy storage ceramic is 7.02 J / cm < 3 >-10.55 J / cm < 3 >, and the energy storage efficiency is 91.7%-94.2%.

Description

Technical Field

[0001] This application relates to the field of dielectric energy storage ceramic materials, specifically to a potassium sodium niobate-based energy storage ceramic and its preparation method and application. Background Technology

[0002] High-performance dielectric energy storage devices are crucial for next-generation electronic and electrical systems due to their superior power density. Compared to various batteries and electrochemical capacitors, dielectric capacitors offer excellent charge / discharge speeds and ultra-high power densities. However, the relatively low energy density and / or low efficiency of dielectric capacitors still hinder their further miniaturization, limiting their widespread application.

[0003] The energy density of a dielectric capacitor is determined by the applied electric field and the dielectric polarization. To achieve extremely high energy density and efficiency, three key parameters must be optimized simultaneously: high maximum polarization, low remanent polarization, and high breakdown strength. However, these parameters are significantly interrelated, posing a major challenge to their synergistic optimization. Materials with high maximum polarization are often accompanied by high remanent polarization, which leads to significant hysteresis losses due to ferroelectric domain wall movement under an external electric field, thereby reducing efficiency.

[0004] Traditional techniques for suppressing hysteresis loss primarily employ elemental doping and / or solid solution methods to break down long-range ordered micrometer-scale ferroelectric domains into short-range ordered nanodomains, thereby lowering the domain flipping energy barrier. Furthermore, increased efficiency reduces Joule heating caused by hysteresis loss during polarization flipping, thus mitigating localized thermal effects and improving the breakdown electric field. However, the main limitation of this strategy lies in the significant reduction of maximum polarization intensity.

[0005] Therefore, the preparation of a ceramic with both high energy storage density and high energy storage efficiency has very important application value. Summary of the Invention

[0006] Based on this, in order to solve the technical problem of simultaneously improving the energy storage density and energy storage efficiency of energy storage ceramics, this application provides a potassium sodium niobate-based energy storage ceramic, its preparation method and application.

[0007] This application provides a potassium sodium niobate-based energy storage ceramic, the chemical composition of which includes: (1-x)(0.55K) 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y Ti 0.9 Zr 0.1 O3, where 0 < x ≤ 0.4 and -0.05 ≤ y ≤ 0.1.

[0008] In some of these embodiments, 0.1 ≤ x ≤ 0.3, -0.05 ≤ y ≤ 0.05.

[0009] In some embodiments, the breakdown field strength of the potassium sodium niobate-based energy storage ceramic is 420 kV / cm-520 kV / cm.

[0010] In some embodiments, the potassium sodium niobate-based energy storage ceramic has an energy storage density of 7.02 J / cm³-10.55 J / cm³ and an energy storage efficiency of 91.7%-94.2%.

[0011] This application also provides a method for preparing the aforementioned potassium sodium niobate-based energy storage ceramic, comprising the following steps: S1, based on the chemical composition (1-x) (0.55K) 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y Ti 0.9 Zr 0.1 O3 stoichiometrically weighed K source, Na source, Nb source, Ba source, Ti source, Bi source and Zr source, mixed and ground, then dried to obtain mixed powder; S2. The mixed powder is calcined to obtain potassium sodium niobate-based energy storage ceramic precursor powder; S3. The potassium sodium niobate-based energy storage ceramic precursor powder and binder are mixed, pressed into sheets, and the binder is removed to obtain a potassium sodium niobate-based energy storage ceramic green body. S4. Sinter the potassium sodium niobate-based energy storage ceramic green body to prepare potassium sodium niobate-based energy storage ceramic.

[0012] In some embodiments, the K source includes K2CO3.

[0013] In some embodiments, the Na source includes Na2CO3.

[0014] In some embodiments, the Nb source includes Nb2O5.

[0015] In some embodiments, the Ba source is selected from at least one of BaCO3 and BaO.

[0016] In some embodiments, the Ti source includes TiO2, the Bi source includes Bi2O3, and the Zr source includes ZrO2.

[0017] In some embodiments, the grinding speed is 200 r / min-500 r / min.

[0018] In some embodiments, the grinding time is 12h-24h.

[0019] In some embodiments, the drying temperature is 90°C-120°C.

[0020] In some embodiments, the drying time is 2h-6h.

[0021] In some embodiments, the calcination temperature is 600℃-800℃ and the time is 2h-3h.

[0022] In some embodiments, the pressure of the compressed sheet is 2MPa-8MPa.

[0023] In some embodiments, the pressure holding time is 1 min to 2 min.

[0024] In some embodiments, the temperature of the adhesive removal is 500℃-600℃, and the time for adhesive removal is 2h-4h.

[0025] In some embodiments, the adhesive comprises a 5 wt% aqueous solution of polyvinyl alcohol.

[0026] In some embodiments, the sintering temperature is 1000℃-1200℃, and the sintering time is 2h-3h.

[0027] Another aspect of this application provides the application of the potassium sodium niobate-based energy storage ceramic or the potassium sodium niobate-based energy storage ceramic prepared by the method in the preparation of pulse power technology and power electronic system products.

[0028] The potassium sodium niobate-based energy storage ceramic provided in this application achieves synergistic optimization of high energy storage density and high energy storage efficiency through specific chemical composition design. By adjusting the ratio of x and y, the domain structure and defect composition in this system can be effectively controlled. From a thermodynamic perspective, by constructing a domain structure of polymorphic relaxor phases, polarization anisotropy and domain flipping energy barriers can be further weakened, thereby forming a flatter domain flipping path and minimizing hysteresis loss. Furthermore, transforming point defects into defect complexes can significantly improve the material resistivity and breakdown field strength. In addition to affecting resistivity and breakdown behavior, defect complexes can also change the polarization characteristics of the material. Its polarizability is three orders of magnitude higher than that caused by electron / ion displacement, which provides a new path to enhance the maximum polarization intensity. Through the synergistic effect of the above mechanisms, the potassium sodium niobate-based energy storage ceramic of this application achieves an energy storage density of 7.02 J / cm³-10.55 J / cm³ and an energy storage efficiency of 91.7%-94.2% at room temperature and 100 Hz. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a STEM image of the potassium sodium niobate-based energy storage ceramic of Example 1 of this application; Figure 2 This is the TSDC diagram of the potassium sodium niobate-based energy storage ceramic of Example 1 of this application; Figure 3 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Example 1 of this application; Figure 4 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Example 2 of this application; Figure 5 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Example 3 of this application; Figure 6 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Example 4 of this application; Figure 7 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Comparative Example 1 of this application; Figure 8 This is the PE curve measured at the maximum breakdown strength of the potassium sodium niobate-based energy storage ceramic of Comparative Example 2 of this application. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the embodiments and examples. It should be understood that these embodiments and examples are for illustrative purposes only and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to enable a more thorough and comprehensive understanding of the disclosure of the present application. It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the spirit of the present application, and the equivalent forms obtained also fall within the protection scope of the present application. Furthermore, numerous specific details are set forth in the following description to provide a fuller understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0033] the term Unless otherwise stated or in case of contradiction, the terms or phrases used herein shall have the following meanings: The terms "and / or," "or / and," and "and / or" as used herein include any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that in this application, the technical solution undoubtedly includes technical solutions connected by "logical AND," and also undoubtedly includes technical solutions connected by "logical OR." For example, "A and / or B" includes three parallel solutions: A, B, and A+B. For example, the technical solution of "A, and / or, B, and / or, C, and / or, D" includes any one of A, B, C, and D (that is, a technical solution that is connected by "logical OR"), as well as any and all combinations of A, B, C, and D, that is, combinations of any two or three of A, B, C, and D, and also combinations of all four of A, B, C, and D (that is, a technical solution that is connected by "logical AND").

[0034] In this application, the terms "multiple", "various", "multiple times", "multi-dimensional", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0035] The terms “combinations of,” “any combination of,” and “any combination of” used in this article include all suitable combinations of any two or more of the listed items.

[0036] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0037] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0038] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0039] In this application, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions containing the listed features.

[0040] In this application, numerical intervals (i.e., numerical ranges) are involved. Unless otherwise specified, the selected numerical distributions within the aforementioned numerical intervals are considered continuous and include the two endpoints (i.e., the minimum and maximum values) of the numerical range, as well as every value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints. In this document, this is equivalent to directly listing every integer. For example, if t is an integer selected from 1 to 10, it means that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Furthermore, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges to which they are included.

[0041] Unless otherwise specified, the temperature parameters in this application are permitted to be either constant-temperature treatment or variations within a certain temperature range. It should be understood that the constant-temperature treatment allows temperature fluctuations within the precision range of the instrument control, such as ±5℃, ±4℃, ±3℃, ±2℃, or ±1℃.

[0042] In this application, % (w / w) and wt% both represent weight percentage, % (v / v) refers to volume percentage, and % (w / v) refers to mass-volume percentage.

[0043] The first aspect of this application provides a potassium sodium niobate-based energy storage ceramic, the chemical composition of which includes (1-x)(0.55K) 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y Ti 0.9 Zr 0.1 O3, where 0 < x ≤ 0.4 and -0.05 ≤ y ≤ 0.1.

[0044] The potassium sodium niobate-based energy storage ceramic provided in this application achieves synergistic optimization of high energy storage density and high energy storage efficiency through specific chemical composition design. By adjusting the ratio of x and y, the domain structure and defect composition in this system can be effectively controlled. From a thermodynamic perspective, by constructing a domain structure of polymorphic relaxor phases, polarization anisotropy and domain flipping energy barriers can be further weakened, thereby forming a flatter domain flipping path and minimizing hysteresis loss. Furthermore, transforming point defects into defect complexes can significantly improve the material resistivity and breakdown field strength. In addition to affecting resistivity and breakdown behavior, defect complexes can also change the polarization characteristics of the material. Its polarizability is three orders of magnitude higher than that caused by electron / ion displacement, which provides a new path to enhance the maximum polarization intensity. Through the synergistic effect of the above mechanisms, the potassium sodium niobate-based energy storage ceramic of this application achieves an energy storage density of 7.02 J / cm³-10.55 J / cm³ and an energy storage efficiency of 91.7%-94.2% at room temperature and 100 Hz.

[0045] In some embodiments, 0.1 ≤ x ≤ 0.3, -0.05 ≤ y ≤ 0.05. Within this parameter range, the energy storage density and energy storage efficiency of potassium sodium niobate-based energy storage ceramics are further improved.

[0046] In some embodiments, the breakdown field strength of the potassium sodium niobate-based energy storage ceramic is 420 kV / cm-520 kV / cm at 1000℃-1200℃. High breakdown field strength is a key factor in achieving high energy storage density.

[0047] In some embodiments, at room temperature and 100 Hz, the energy storage density of the potassium sodium niobate-based energy storage ceramic is 7.02 J / cm³-10.55 J / cm³, and the energy storage efficiency is 91.7%-94.2%.

[0048] This application also provides a method for preparing the potassium sodium niobate-based energy storage ceramic, comprising the following steps: S1: Preparation of mixed powder In this step, based on the chemical composition (1-x)(0.55K) 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y Ti 0.9 Zr 0.1The K, Na, Nb, Ba, Ti, Bi, and Zr sources were weighed out according to the stoichiometric ratio, mixed, ground, and dried to obtain a mixed powder. The grinding process ensures thorough mixing and particle refinement of all raw materials, creating favorable conditions for the subsequent calcination reaction. It should be noted that the K, Na, Nb, Ba, Ti, Bi, and Zr sources are conventional compounds in the art, and those skilled in the art can select them according to actual needs. For example, the K source includes K₂CO₃, the Na source includes Na₂CO₃, the Nb source includes Nb₂O₅, the Ba source includes at least one of BaCO₃ and BaO, the Ti source includes TiO₂, the Bi source includes Bi₂O₃, and the Zr source includes ZrO₂.

[0049] According to embodiments of this application, the grinding speed is 200 r / min-500 r / min, and the grinding time is 12h-24h. By controlling the grinding speed and time within the above range, the materials can be mixed more uniformly, ensuring particle size and thus improving the efficiency of the calcination curing reaction. Those skilled in the art will understand that grinding is a conventional operation in the field, using conventional equipment, such as a ball mill with nitrile oxide balls as the grinding media. Furthermore, the drying temperature is 90℃-120℃, and the drying time is 2h-6h, thereby removing as much moisture as possible from the mixture.

[0050] S2: Calcining the mixed powder In this step, the mixed powder is calcined. Calcination promotes a more complete and uniform solid-phase chemical reaction of each raw material, resulting in a solid solution with a fixed composition and forming the main crystalline phase. At the same time, it reduces carbon dioxide and moisture in the raw materials, thereby reducing shrinkage and deformation of the green body during sintering, avoiding cracking of the product and better controlling its shape and size.

[0051] According to embodiments of this application, the calcination temperature is 600℃-800℃, and the time is 2h-3h. The applicant has found that if the calcination temperature is too high and the time is too long, the grains after calcination will be too large, reducing the sintering driving force and hindering sintering; if the calcination temperature is too low and the time is too short, the main crystalline phase will be indistinct, and many impurity phases will be generated. Therefore, the calcination temperature of this application is 600℃-800℃, and the time is 2h-3h, which can remove volatiles from the raw materials to prevent excessive shrinkage and cracking during sintering, while also forming the desired crystalline phase.

[0052] S3: Potassium sodium niobate-based energy storage ceramic precursor powder and binder are mixed and then pressed into sheets. In this step, the potassium sodium niobate-based energy storage ceramic precursor powder obtained by calcination and the binder are thoroughly mixed and stirred in a mortar, aged for 2 hours, and then passed through a 150-mesh sieve. The mixture is then pressed into tablets in an automatic tablet press at a pressure of 2 MPa-8 MPa for 1-2 minutes. Finally, the tablets are placed in a muffle furnace and subjected to binder removal at 500℃-600℃ for 2-4 hours to obtain the potassium sodium niobate-based energy storage ceramic green body. Further, the binder comprises at least one of a 5wt%-8wt% aqueous solution of polyvinyl alcohol and a 5wt%-8wt% ethanol solution of polyvinyl butyral. Specifically, 1g of potassium sodium niobate-based energy storage ceramic precursor powder is mixed with 2-3 drops of the above binder.

[0053] S4: Sintering potassium sodium niobate-based energy storage ceramic green bodies In this step, potassium sodium niobate-based energy storage ceramic green bodies are placed in a muffle furnace for sintering, thereby obtaining potassium sodium niobate-based energy storage ceramics with excellent density and certain strength, thus achieving ceramic densification.

[0054] According to embodiments of this application, the sintering temperature is 1000℃-1200℃, and the sintering time is 2h-3h. This application finds that the selection of sintering temperature and holding time has a significant impact on the densification degree and grain size of potassium sodium niobate-based energy storage ceramics, and directly determines their energy storage performance. Specifically, excessively high sintering temperatures or excessively long holding times may lead to localized melting of the sample, abnormal grain growth, impurity phase generation, and porosity formation, resulting in an inhomogeneous microstructure; while excessively low temperatures or short holding times will lead to insufficient ceramic densification, decreased mechanical strength, and difficulty in avoiding the presence of impurity phases. Based on the above findings, this application preferably sintersects at a temperature range of 1000℃-1200℃ for 2h-3h. This condition helps to improve the density and mechanical strength of the ceramic, promotes the formation of a pure phase structure, and thus effectively optimizes the overall energy storage performance of potassium sodium niobate-based energy storage ceramics.

[0055] Therefore, this method can be used to prepare potassium sodium niobate-based energy storage ceramics with high energy storage density and efficiency. Furthermore, the preparation process is simple, reproducible, and has low requirements for production equipment and facilities, which is conducive to large-scale, industrialized production. The prepared ceramics also exhibit stable properties. It should be noted that the characteristics and advantages described above for potassium sodium niobate-based energy storage ceramics also apply to this method, and will not be repeated here.

[0056] In some embodiments, the potassium sodium niobate-based energy storage ceramic or the potassium sodium niobate-based energy storage ceramic prepared by the method is used in the preparation of pulse power technology and power electronic system products.

[0057] The embodiments of this application will be described in detail below with reference to examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this application, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0058] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.

[0059] It should be understood that in the various embodiments of this application, the order of the above-mentioned processes does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. Example 1

[0060] This embodiment provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0061] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, TiO2 powder, Bi2O3 powder, and ZrO2 powder, based on 0.7 (0.55K). 0.5 Na 0.5 NbO3-0.45BaTiO3)-0.3(Bi 0.475 Na 0.525 Ti 0.9 Zr 0.1 Weigh the raw materials according to the stoichiometric ratio of O3.

[0062] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0063] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0064] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1100℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic. Example 2

[0065] This embodiment provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0066] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, TiO2 powder, Bi2O3 powder, and ZrO2 powder, based on 0.7 (0.55K). 0.5 Na 0.5 NbO3-0.45BaTiO3)-0.3(Bi 0.45 Na 0.55 Ti 0.9 Zr 0.1 Weigh the raw materials according to the stoichiometric ratio of O3.

[0067] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0068] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0069] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1125℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic. Example 3

[0070] This embodiment provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0071] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, TiO2 powder, Bi2O3 powder, and ZrO2 powder, based on 0.7 (0.55K). 0.5 Na 0.5 NbO3-0.45BaTiO3)-0.3(Bi 0.525 Na 0.475 Ti 0.9 Zr 0.1 Weigh the raw materials according to the stoichiometric ratio of O3.

[0072] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0073] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0074] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1075℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic. Example 4

[0075] This embodiment provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0076] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, TiO2 powder, Bi2O3 powder, and ZrO2 powder, based on 0.7 (0.55K). 0.5 Na 0.5 NbO3-0.45BaTiO3)-0.3(Bi 0.55 Na 0.45 Ti 0.9 Zr 0.1 Weigh the raw materials according to the stoichiometric ratio of O3.

[0077] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0078] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0079] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1050℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic. Comparative Example 1

[0080] This comparative example provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0081] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, and TiO2 powder, based on the chemical composition of 0.55K. 0.5 Na 0.5 Weigh the raw materials according to the stoichiometric ratio of NbO3-0.45BaTiO3.

[0082] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0083] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0084] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1100℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic. Comparative Example 2

[0085] This comparative example provides a potassium sodium niobate-based energy storage ceramic and its preparation method.

[0086] The raw materials for preparing potassium sodium niobate-based energy storage ceramics include: K2CO3 powder, Na2CO3 powder, Nb2O5 powder, BaCO3 powder, TiO2 powder, Bi2O3 powder, and ZrO2 powder. Based on the chemical composition 0.7 (0.55K... 0.5 Na 0.5 NbO3-0.45BaTiO3)-0.3(Bi 0.5 Na 0.5 Ti 0.9 Zr 0.1 Weigh the raw materials according to the stoichiometric ratio of O3.

[0087] The preparation method of potassium sodium niobate-based energy storage ceramics includes the following steps: (1) The powder was loaded into a 250mL nylon ball mill jar, and alcohol was added according to the mass ratio of raw material powder to anhydrous ethanol of 1:2. The mixture was ball milled at 360r / min for 18h and the slurry was separated. The mixture was dried at 100℃ for 4h and then placed in a muffle furnace and calcined at 750℃ for 3h at a heating rate of 5℃ / min to obtain potassium sodium niobate-based energy storage ceramic precursor powder.

[0088] (2) The above-mentioned potassium sodium niobate-based energy storage ceramic precursor powder and a 5wt% polyvinyl alcohol aqueous solution were thoroughly mixed in an agate mortar. The ratio of precursor powder to binder was 1g precursor powder: 2 drops of 5wt% polyvinyl alcohol aqueous solution. After aging for 2 hours, the mixture was passed through a 150-mesh sieve. 0.4g of powder was poured into a 10cm diameter tablet mold and pressed into shape in an automatic tablet press at a pressure of 4MPa for 1 minute. The tablet was then placed in a muffle furnace and heated to 600℃ at a heating rate of 2℃ / min. The temperature was maintained for 3 hours to remove the binder and obtain a potassium sodium niobate-based energy storage ceramic green body.

[0089] (3) The above potassium sodium niobate-based energy storage ceramic green body is slowly transferred to a muffle furnace and heated to 1100℃ at a heating rate of 5℃ / min and held for 3h to obtain potassium sodium niobate-based energy storage ceramic.

[0090] Data aggregation and data analysis Performance testing methods: Breakdown field strength test: The breakdown field strength of the sample was tested at a frequency of 100Hz at room temperature using a high-voltage breakdown tester.

[0091] Energy storage performance testing: The hysteresis loop (PE curve) of the sample was tested using a ferroelectric tester at 100 Hz and room temperature. The energy storage density and energy storage efficiency were calculated based on the PE curve.

[0092] Microstructure analysis: The domain structure of the sample was observed using scanning transmission electron microscopy (STEM).

[0093] Defect analysis: Thermally stimulated depolarization current (TSDC) technology was used to analyze the defect types in the samples.

[0094] The performance of the potassium sodium niobate-based energy storage ceramics of Examples 1-4 and Comparative Examples 1-2 was measured, as follows: (1) STEM analysis was performed on the potassium sodium niobate-based energy storage ceramic of Example 1, and the results are as follows: Figure 1 .from Figure 1 It can be seen that in the sample of Example 1, tetragonal domains (T), rhombohedral domains (R) and orthorhombic domains (O) coexist, which is beneficial to reducing polarization anisotropy and domain flipping barriers, thereby improving efficiency.

[0095] (2) TSDC analysis was performed on the potassium sodium niobate-based energy storage ceramic of Example 1, and the results are as follows: Figure 2 Between 0-150℃, there is a current peak. As the voltage increases, the maximum current of the current peak gradually increases, but the position of the current peak remains unchanged. This indicates that there is a defective complex in the sample of Example 1.

[0096] (3) PE curve tests were performed on the potassium sodium niobate-based energy storage ceramics of Examples 1-4 and Comparative Examples 1-2, respectively, as shown in the figure. Figure 3-8 As shown. From Figure 3-6 It can be seen that the breakdown field strength of the potassium sodium niobate-based energy storage ceramics in Examples 1-4 can reach 420 kV / cm-520 kV / cm, the energy storage density under the maximum electric field is 7.02 J / cm3-10.55 J / cm3, and the efficiency is 91.7%-94.2%. Figure 7 and Figure 8 It can be seen that the breakdown field strength of potassium sodium niobate-based energy storage ceramics in Comparative Examples 1 and 2 is significantly reduced to 200kV / cm-380kV / cm, and therefore their energy storage density is reduced to 1.47 J / cm3-5.67 J / cm3, with an efficiency of 92.9%-96.3%.

[0097] The specific performance test results of the potassium sodium niobate-based energy storage ceramics of Examples 1-4 and Comparative Examples 1-2 are shown in Table 1.

[0098] Table 1: Test Results of Examples and Comparative Examples

[0099] Data Analysis: The potassium sodium niobate-based energy storage ceramics in Examples 1-4 all exhibited excellent energy storage performance, with breakdown field strengths reaching 420-520 kV / cm and energy storage densities of 7.02-10.55 J / cm³, while maintaining a high energy storage efficiency of 91.7%-94.2%. In contrast, the energy storage performance of Comparative Examples 1-2 was significantly reduced, especially Comparative Example 1, which had a breakdown field strength of only 200 kV / cm and an energy storage density of only 1.47 J / cm³. Although its energy storage efficiency was relatively high (96.3%), its overall energy storage performance was far lower than that of the Examples.

[0100] Example 1 exhibits the best overall performance, with a breakdown field strength as high as 520 kV / cm, an energy storage density of 10.55 J / cm³, and an energy storage efficiency of 94.2%. STEM analysis shows that the sample of Example 1 simultaneously contains tetragonal (T), rhombohedral (R), and orthorhombic (O) domains. This multi-state relaxor phase structure effectively reduces polarization anisotropy and domain flipping barriers, thereby improving energy storage efficiency. TSDC analysis shows the presence of defect complexes in the sample of Example 1. These defect complexes significantly increase the material resistivity and breakdown field strength, while also enhancing the maximum polarization intensity.

[0101] Comparative Example 1 does not contain the second phase (Bi 0.5-y Na 0.5+y ), Ti 0.9 Zr 0.1 O3. Therefore, it is impossible to form a polymorphic relaxation phase structure and a defect complex, resulting in a significant reduction in both the breakdown field strength and the maximum polarization intensity. The energy storage density is only 14% of that in Example 1. Although Comparative Example 2 contains the second phase, y = 0 and the Na / Bi ratio is not optimized. Therefore, the formation of the defect complex is insufficient, and the breakdown field strength and the maximum polarization intensity are lower than those in Example 1.

[0102] The energy storage density of Example 3 is the lowest among the examples (7.02 J / cm³), and the breakdown field strength is also the lowest (420 kV / cm), which is related to its relatively low sintering temperature (1075 °C). The lower sintering temperature results in insufficient densification of the ceramic and a higher porosity, thus reducing the breakdown field strength and the energy storage density. The y value of Example 4 (0.05) is at the upper limit of the parameter range of this application, and the Bi content is relatively high, which may cause partial Bi volatilization and affect the material properties. Examples 5 and 6 correspond to x = 0.2 and x = 0.4 respectively, both within the x range of Claim 1 (0 < x ≤ 0.4), showing good energy storage performance and verifying the wide applicability of the chemical composition of this application.

[0103] The above-described examples only represent several implementation manners of this application, which are convenient for understanding the technical solutions of this application specifically and in detail, but should not be construed as limiting the scope of patent protection of this application. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several modifications and improvements can still be made, and these all belong to the protection scope of this application. In addition, it should be understood that after reading the above teachings of this application, those skilled in the art can make various changes or modifications to this application, and the equivalent forms obtained also fall within the protection scope of this application. It should also be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solutions provided in this application are all within the protection scope of the appended claims of this application. Therefore, the protection scope of this patent application shall be subject to the content of the appended claims, and the specification can be used to explain the content of the claims.

Claims

1. A potassium sodium niobate-based energy storage ceramic, characterized in that, The chemical composition of the potassium sodium niobate-based energy storage ceramic includes: (1-x)(0.55K 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y ) Ti 0.9 Zr 0.1 O3, of which 0<x≤0.4, -0.05≤y≤0.

1.

2. The potassium sodium niobate-based energy storage ceramic according to claim 1, characterized in that, 0.1≤x≤0.3, -0.05≤y≤0.

05.

3. The potassium sodium niobate-based energy storage ceramic according to claim 1, characterized in that, The breakdown field strength of the potassium sodium niobate-based energy storage ceramic is 420kV / cm-520kV / cm.

4. The potassium sodium niobate-based energy storage ceramic according to any one of claims 1-3, characterized in that, The potassium sodium niobate-based energy storage ceramic has an energy storage density of 7.02 J / cm³-10.55 J / cm³ and an energy storage efficiency of 91.7%-94.2%.

5. The method for preparing potassium sodium niobate-based energy storage ceramics according to any one of claims 1-4, characterized in that, Includes the following steps: S1, based on the chemical composition (1-x) (0.55K) 0.5 Na 0.5 NbO3-0.45BaTiO3)-x(Bi 0.5-y Na 0.5+y Ti 0.9 Zr 0.1 O3 stoichiometrically weighed K source, Na source, Nb source, Ba source, Ti source, Bi source and Zr source, mixed and ground, then dried to obtain mixed powder; S2. The mixed powder is calcined to obtain potassium sodium niobate-based energy storage ceramic precursor powder; S3. The potassium sodium niobate-based energy storage ceramic precursor powder and binder are mixed, pressed into sheets, and the binder is removed to obtain a potassium sodium niobate-based energy storage ceramic green body. S4. Sinter the potassium sodium niobate-based energy storage ceramic green body to prepare potassium sodium niobate-based energy storage ceramic.

6. The method for preparing potassium sodium niobate-based energy storage ceramics according to claim 5, characterized in that, S1 satisfies one or more of the following conditions: (1) The K source includes K2CO3; (2) The Na source includes Na2CO3; (3) The Nb source includes Nb2O5; (4) The Ba source is selected from at least one of BaCO3 and BaO; (5) The Ti source includes TiO2, the Bi source includes Bi2O3, and the Zr source includes ZrO2; (6) The grinding speed is 200 r / min-500 r / min; (7) The grinding time is 12h-24h; (8) The drying temperature is 90℃-120℃; and (9) The drying time is 2h-6h.

7. The method according to claim 5, characterized in that, In step S2, the calcination temperature is 600℃-800℃ and the time is 2h-3h.

8. The method according to claim 5, characterized in that, S3 satisfies one or more of the following conditions: (1) The pressure for compressing the sheet is 2MPa-8MPa; (2) The pressure holding time is 1 min to 2 min; (3) The temperature of the glue removal is 500℃-600℃, and the time of glue removal is 2h-4h; as well as (4) The adhesive comprises 5 wt% of a polyvinyl alcohol aqueous solution.

9. The method according to claim 5, characterized in that, In step S4, the sintering temperature is 1000℃-1200℃, and the sintering time is 2h-3h.

10. The application of the potassium sodium niobate-based energy storage ceramic according to any one of claims 1-4 or the potassium sodium niobate-based energy storage ceramic prepared by any one of claims 5-9 in the preparation of pulse power technology and power electronic system products.

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